Washington horse diagnosed with West Nile virus

A horse in Franklin County, Wash., is the first in the state this year to be diagnosed with West Nile virus.

OLYMPIA — A mosquito infected with West Nile virus has brought down a horse in Central Washington.

The 7-year-old quarter horse gelding was euthanized this week after suffering paralysis in the hindquarters, state officials said Wednesday.

It’s the first case of West Nile virus in a horse reported in Washington this year.

The Washington Animal Disease Diagnostic Laboratory in Pullman confirmed Monday that the horse near Pasco in Franklin County tested positive for the mosquito-borne virus.

Mosquitoes pick up the virus by feasting on infected birds. The virus does not pass from horse to horse or from horses to humans.

The acting state veterinarian, Paul Kohrs, said the annual number of cases of West Nile virus can range in Washington from zero to dozens.

“It’s a fairly common occurrence this time of year,” he said.

The state Veterinarian’s Office advised horse owners to check their animals for signs of the virus. Symptoms include loss of coordination and appetite, fever, muscle stiffness and weakness in the hindquarters.

The Washington Department of Health announced Monday that a Walla Walla County man had been diagnosed with the virus, the first human case in the state this year.

Last year, horses in Pasco and Outlook, which is in Yakima County, were the only two equine cases of West Nile virus in Washington. There were six cases in Oregon and 10 in Idaho.

The two Washington cases were found in late September and early October.

The virus is fatal to horses in about one-third of the cases. In some cases, the animal shows no symptoms.

Health officials said the best way to guard against the virus is to eliminate standing water, where mosquitoes breed.

“If I’ve got several animals, especially horses, I’d make every effort to walk around the yard and eliminate the standing water that I see and make sure I’m not providing breeding ground for the mosquitoes,” Kohrs said.

The horse that contracted West Nile virus had never traveled out of state and came home with another horse from a Washington feedlot, according to the agriculture department.

The owner had nine other horses — eight of which had been vaccinated against West Nile virus, department spokesman Mike Louisell said.

The other horse has now been vaccinated against the virus, he said.

The Washington Veterinarian’s Office asked veterinarians treating horses with symptoms of West Nile virus to report the cases to the state office at 360-902-1881.